1. Field of the Invention
This invention relates generally to adjustable wrenches wherein wedge elements are used to provide quick adjustment. This invention is most suitable for quick adjustable wrenches of the type wherein the jaws extend longitudinally from the handle. This type of wrench is generally referred to as an adjustable open ended wrench.
2. Description of the Prior Art
In the most common type of adjustable wrench a worm gear and a journaled jaw member interact to change the relative location of the fixed and movable jaws. A pin rotatably holds the worm gear in a slot that extends through the handle of the wrench. The worm gear contacts a journaled rear portion of the movable jaw. The movable jaw slides in a groove defined by the handle to a location controlled by the worm gear. U.S. Pat. No. 2,722,150 shows the general arrangement of this type of wrench. The worm gear arrangement of this typical wrench design always leaves some play between the jaws. This play results in the wrench sometimes slipping under pressure and thus detracting from the reliability of such devices.
Many adjustable wrench designs have been proposed that attempt to improve the adjustability and reliability of such wrenches. Such wrench designs include U.S. Pat. No. 1,397,214 wherein a slot in the handle of wrench retains a grooved wedge that a spring biases toward a slidably mounted movable jaw having complementary grooves for holding the jaw in position. The movement of the wedge is relatively quick which in turn allows quick adjustment of the wrench.
A number of other quick adjustment wrench designs use a series of wedges or ramps to quickly adjust the position of the movable jaw. Basic wedge designs in adjustable wrenches are well known and depicted in U.S. Pat. Nos. 1,511,526, 1,481,250, 1,004,561, 1,514,017 and 1,427,918. Examples of wedge designs adapted for use in open adjustable type wrenches are shown in U.S. Pat. Nos. 2,948,175 and 1,389,487 wherein a wedge cooperates with an inclined surface to move the wedge forward in compression against an opposing surface of the movable jaw. Pressure exerted by the wedge locks the jaw in place until displacement of the wedge along the surface of the ramp releases the jaw. Another wedge type wrench design is shown in U.S. Pat. No. 4,903,556 where a wedge is contained in an inclined slot that extends through a handle portion of the wrench. The wedge has a flat surface on one side that acts against a surface of the slot and a tapered surface that acts against a tapered surface on the back of a movable jaw.
Although the wedge type wrench designs offer quick adjustment and generally less play than the worm gear type wrenches, the wedge type designs can still slip under heavy load. In these wedge type designs the wedge acts against the walls of the slot. Pressure on the wedge causes the wedge to move or give slightly. This small amount of give still results in slippage of the wrench that deforms nuts and bolts and can cause injury to the user.
One object of the invention is to provide a quickly adjustable wrench of the open adjustable type that has a reduced amount of play between the jaws relative to other wedge type open adjustable wrench designs.
Another object of this invention is to provide a quickly adjustable open type wrench having a simplified wedge design.
It has been discovered that the problem with the other open adjustable wrench designs that use a wedge in a slot for quick adjustment is that the wedges are always arranged in a way that will tend to enlarge the slot. As this enlarging occurs the wedge can slip slightly or a small relative movement of the jaws will occur, thereby causing the wrench to become loose.